Process of treating metal plate.



No. 713,440. Patented Nov. ll, I902.

.1. nowau. & s. .1. DREW. PROCESS OF TREATING METAL PLATE.

(Application filed July 27, 1901.)

(N0 Iodel.)

AT GENE).-

"m: NORRIS PETERS co. woman-mo" WASHINGTON. n. c.

' UNITED STATES PATENT OFFICE.

JENKIN IIOWVELL AND SAMUEL J. DREW, OF JOLIET, ILLINOIS.

PROCESS OF TREATING METAL PLATE.

SPECIFICATION forming part of Letters Patent No. 713,440, dated November11, 1902. Application filed July 2'7, 1901. Serial No. 6 1 Specimens-lTo all whom, it may concern/.-

Be it known that we, J ENKIN HOWELL and SAMUEL J. DREW, citizens of theUnited States, residing at Joliet, in the county of Will and State ofIllinois, have invented certain new and useful Improvements in Processesof Treating Metal Plates; and we do hereby declare the following to be afull, clear, and exact description of the invention, such as will enableothers skilled in the art to which it appertains to make and use thesame.

Our invention relates to improvements in the process of treatingsheet-metal plates in the production of tin-plate. Important resultsobtained by our improved process are the reduction of the number oftimes the plates must be handled manually, the saving of time betweenthe pickling and the annealing steps, the thorough cleansing of theplates, whereby the formation of green or other patches in theannealing-is prevented,

and economy in the treatment as compared with the methods in common use.

In the manufacture of tin-plate as commonly carried on after the platesare removed from the usual pickling-bath they are washed in water orswilled to remove the deposits of the pickling, then placed fiatwise orsuperimposed horizontallyin annealin g-pots,which are run intoreverberatory furnaces,to the flames of which the sides of the pots aresubjected until the plates are red-hot, after which they are allowed tocool, when they are ready for the rolls or for further treatment. In sotreating the plates they must be separately handledonoe when placed inthe picklingbath, a second time when taken out of such bath, and a thirdtime when placed in the annealing-pots. In spite of great care in thewashing and annealing of these plates in the manner described foreignsubstances adhere to the plates from the pickling-bath, which result inthe formation of green and other patches during the annealing, with theresult that the plates so damaged are rendered entirely unmerchantableor are much reduced in value.

In carrying into effect our process we preferably use a furnace such asis shown in the accompanying drawing, which shows a crosssection of thefurnace used for annealing the plates.

Referring to the drawing in detail, A represents the furnace-ovens; B,the fire-box; S, the smoke-stacks; D,the annealing-boxes supported onwheeled trucks E; O, the plates arranged on edge in the boxes, and b theashpit of the furnace.

In the application of our improved process we take the plates after theyleave the usual pickling-bath and while set on edge in theannealing-boxes and wash or swill them with a weak solution of hot waterand muriatic acid, about one and one-half gallons of acid being used toone hundred gallons" of water in the solution. After so swilling theplates we subject them to a final washing of limewater, in which we useone hundred pounds of lime to one hundred gallons of water. The weakacid-bath removes the deposits left on the plates from the pickling-bathor makes them solvent, so that they may be efiectively removed by thebath of lime-water referred to, so that when the plates are ready to goto the annealing-furnace they are clean and sufficiently warm from thehot acid solution and the hot lime-Water to almost dry them. The platesare left in the same pots or boxes in which they have been pickled andswilled and in the same position-i. 6., on edge and not in contact witheach otherand are run into the annealing-furnace, where they aresubjected to superheated air, which is per-= mitted to come into directcontact with the faces of the plates by reason of the position andarrangement of the plates described. The dry heat of the furnace-ovensquickly takes up any moisture which may be left on the plates from thebaths described and they become quickly and thoroughly heated, thuseffecting their annealing in much less time than with the usual methods.

We are aware that it is not new to subject iron plates to a swilling oflime-water, nor is it new to anneal them in ovens as distinguished fromreverberatory furnaces, and we therefore do not claim such methods; but

What we claim, and desire to obtain by Letters Patent, is-

1. In the process of treating metal plates in the manufacture oftin-plate, first subjecting the plates to the usual pickling-bath, thenwashing the plates in a weak solution of muriatic acid and water, thenwashing the plates in a solution of lime and water, and then subhot airon both sides, substantially as set jecting them to hot air forannealing purforth. poses. In testimony whereof we affix our signa- 2.In the process of treating metal plates tures in presence of twowitnesses. 5 in the manufacture of tin-plate, first subjectin g theplates to the usual pickling-bath, then washing same in a weak solutionof inuriatic acid and hot water, then washing them in a Witnesses:strong solution of lime and water, and finally CHAS. R. BACKUS,

1o subjecting said plates to direct contact with MELVIN RAINVILLE.

